“I have lived my life thinking that as a baby I was naturalised to be Australian and only Australian, and my parents told me that I had until age 21 to actively seek Canadian citizenship. At 21, I chose not to seek dual citizenship, and I have never even visited Canada since leaving at 11 months old.

Greens Senator Larissa Waters arrives with her partner Jeremy Gates and their daughter Alia Joy to announces her resignation in Brisbane. Picture: AAPSource:AAP

“However after Scott’s shock discovery, I immediately sought legal advice, and was devastated to learn that because of 70 year old Canadian laws I had been a dual citizen from birth, and that Canadian law changed a week after I was born and required me to have actively renounced Canadian citizenship.

“I had not renounced since I was unaware that I was a dual citizen.

“Obviously this is something that I should have sought advice on when I first nominated for the Senate in 2007, and I take full responsibility for this grave mistake and oversight. I am deeply sorry for the impact that it will have.”

Australian Greens Senator Larissa Waters breastfeeds her eight-week-old baby Alia Joy during a division in the Senate chamber at Parliament House in Canberra. Picture: AAPSource:AAP

Greens leader Richard Di Natale tweeted that he was “gutted” by the news.

I am gutted by @larissawaters announcement. Parliament & the nation are worse off as a result of the resignation of two amazing leaders.